As portable electronic devices continue to gain popularity, the number of accessories for use with portable electronic devices is increasing. Each accessory typically connects directly to a portable electronic device using a USB wired connection, Bluetooth® wireless connection, or a Near Field Communication (NFC) wireless connection. Once connected, an application running on the portable electronic device may interact with the accessory.
To assist application developers and accessory manufacturers, portable electronic device manufacturers such as Apple and Google have developed communication protocols. For example, Google's “Open Accessory Protocol” or Apple's “Apple Accessory Protocol” may be used to allow communication between a portable electronic device and a connected accessory.
Although these protocols define high-level communication parameters, they do not specify a standard structure or format for messages sent between a portable electronic device and accessories. It is therefore difficult and tedious to implement communication between a portable electronic device and one or more accessories.